A conventional illumination control system 100z for controlling an on/off operation of illumination loads (hereinafter just referred to as “lamps”) installed in an office, a factory, a store or other place will be described with reference to FIG. 35, which is an explanatory view showing a configuration of the conventional illumination control system 100z. The illumination control system 100z includes lamps 1z to 4z, an operation control unit 13z, an illumination control terminal 14z serving as an illumination switch and a commercial AC power source AC4.
Each of lamps 1z to 4z is turned on or off depending on the opening or closing of corresponding contacts of individual relays provided in the operation control unit 13z in a corresponding relationship with the lamps 1z to 4z. For example, if the contacts of the relay corresponding to the lamp 1z are closed, the lamp 1z is turned on. If the contacts of the relay corresponding to the lamp 3z are opened, the lamp 3z is turned off.
The operation control unit 13z is operated by using as a driving power source the electric power supplied from the commercial AC power source AC4. The illumination control terminal 14z outputs to the operation control unit 13z a control signal, so that the operation control unit 13z controls the on/off operation of the respective lamps 1z to 4z in response to the control signal.
In FIG. 35, the lamps 1z to 4z and the commercial AC power source AC4 are electrically connected to the operation control unit 13z by respective power lines. The operation control unit 13z is electrically connected to the illumination control terminal 14z by a signal line S. In this regard, it is assumed that the kinds of the lamps 1z to 4z to be turned on or off upon pushing an operation panel SWy or SWz, i.e., an operation switch unit, of the illumination control terminal 14z shown in FIG. 36 are previously set in the operation control unit 13z. 
As mentioned above, upon pushing the operation panel SWy or SWz shown in FIG. 36, the illumination control terminal 14z outputs to the operation control unit 13z the control signal for controlling the on/off operation of the lamps 1z to 4z. The control signal contains information on the kind of the pushed operation panel SWy or SWz. More specifically, the control signal issued by pushing the operation panel SWy contains information on the kind of the operation panel SWy. Similarly, the control signal issued by pushing the operation panel SWz contains information on the kind of the operation panel SWz. Since the control signal issued by pushing the operation panel SWy or SWz contains information on the kind of the pushed operation panel, the operation control unit 13z can control the on/off operation of the lamps 1z to 4z corresponding to the kind of the pushed operation panel contained in the control signal.
The details of the external structure of the illumination control terminal 14z will now be described with reference to FIG. 36, which shows an external structure of the conventional illumination control terminal 14z. In the description of FIG. 36, the upper, lower, left and right directions running along the paper surface will be defined as upper, lower, left and right directions of the illumination control terminal 14z. Moreover, the direction running perpendicularly forwards with respect to the paper surface will be defined as a front direction and the direction running perpendicularly rearwards with respect to the paper surface will be defined as a rear direction.
The illumination control terminal 14z is visibly installed on a wall surface of an office, a factory, a store or other place. The illumination control terminal 14z shown in FIG. 36 includes a terminal frame K having a left frame 14zl and a right frame 14zr, both of which are arranged at the front side and unified together. A set of operation panel SWy and LED lamp 23z and a set of operation panel SWz and LED lamp 24z are arranged in the left frame 14zl of the illumination control terminal 14z. A display unit 17z formed of, e.g., an LCD (Liquid Crystal Display), and a various buttons 26z to 30z are provided in the right frame 14zr of the illumination control terminal 14z. 
As set forth above, when the operation panel SWy or SWz is pushed, the illumination control terminal 14z outputs to the operation control unit 13z a control signal for controlling the on/off operations of the respective lamps 1z to 4z. The LED lamp 23z arranged in the left frame 14zl of the illumination control terminal 14z emits light in different colors to identify the on/off state of, e.g., the lamps 1z and 2z, which are previously set to be turned on or off upon pushing the operation panel SWy in the operation control unit 13z. The LED lamp 24z arranged in the left frame 14zl of the illumination control terminal 14z emits light in different colors to identify the on/off state of, e.g., the lamps 3z and 4z, which are previously set to be turned on or off upon pushing the operation panel SWz in the operation control unit 13z. For example, the LED lamp 23z emits red light in the on-state of the lamps 1z and 2z. The LED lamp 23z emits green light in the off-state of the lamps 3z and 4z. 
In the right frame 14zr of the illumination control terminal 14z, there are arranged a display unit 17z for displaying the current time or the like, information on the kinds of the operation panels SWy and SWz and a plurality of buttons 26z, 27z, 28z and 30z and the relationships between the operation panel SWy or SWz and the respective lamps 1z to 4z turned on or off upon pushing the operation panel SWy or SWz. The buttons 26z, 27z, 28z and 30z will be described in more detail. The buttons 26z, 27z, 28z and 30z include a mode selection button 28z for selecting one of a normal mode, a timer mode and a current time mode appearing in a mode display area 31z displayed in the upper portion of the display unit 17z. 
Here, the modes in a mode display area 31z will now be described in detail.
The normal mode is a mode indicating that the illumination control system 100z is in operation. The normal mode excludes the current time mode for setting the current time and the timer mode for reviewing the setting programs used in turning on or off one of the lamps 1z to 4z at a specified time. The timer mode a mode in which a user can review the setting programs used in turning on or off one of the lamps 1z to 4z at a time predetermined by the user.
In the following description, the programs for setting therein a plurality of operation parameters to turn on or off the lamps at a set time and for causing the operation control unit 13z to perform the on/off operation of the lamps will be referred to as “setting programs”. Each operation parameter set in the setting programs includes the time at which the lamps are to be turned on or off (hereinafter referred to as “set time”) and the kinds of the lamps to be turned on or off. The setting programs containing such operation parameters are stored in a storage unit (not shown) in the operation control unit 13z. The operation control unit 13z includes an internal clock C1 (not shown). For example, if the current time indicated by the internal clock C1 coincides with a set time included in an operation parameter of a setting program, the lamps set as the control target of the operation parameter of the setting program are turned on or off. The current time mode is a mode for setting the current time of an internal clock C2 (not shown) built in the illumination control terminal 14z. 
Turning back to the description of the buttons 26z, 27z, 28z and 30z, an increment button 26z and a decrement button 27z are provided to increase or decrease the program number of the setting programs that can be reviewed in the timer mode when the timer mode is selected and also to increase or decrease the digits of the current time that can be changed in the current time mode when the current time mode is selected, for example. Further, a setting button 30z is provided to make a setting to display one of the setting programs selected by pushing the increment button 26z or the decrement button 27z and to set the time selected by pushing the increment button 26z or the decrement button 27z as the current time.
The operation control unit 13z which stores the setting programs that can be reviewed in the timer mode includes, as one element thereof, a program timer for controlling the on/off operation of the respective lamps 1z to 4z in accordance with the setting programs. The program timer is disclosed in, e.g., Japanese Patent Application Publication No. 2001-175306. The above disclosure discloses a program timer for a remote monitoring and control system in which transmission signals are sent and received between a plurality of terminals having their own addresses and a transmission unit, both of which are connected to a signal line. Responsive to an on/off signal as a monitoring signal inputted to one of the terminals, the remote monitoring and control system controls the loads connected to other terminals by using the correspondence relationship of the addresses of the terminals.
However, the conventional illumination control terminal 14z shown in FIG. 36 is limited in installation width (Lz) and installation number because it is installed in a narrow installation area of an office, a factory, a store or other place. The display unit 17z and the buttons 26z, 27z, 28z and 30z of the illumination control terminal 14z are all arranged in the narrow area of the right frame 14zr of the illumination control terminal 14z in an integrated manner. This makes it difficult to arrange a display unit having an increased physical size in the right frame 14zr. Use of the small-size display unit 17z makes it troublesome to set the respective parameters in the timer mode.
In case of executing a turning-off program, one of the setting programs, for control of the off operation of the lamps, it is sometimes the case that the lamps are manually turned on again by a third person after execution of the turning-off program. In other words, the turning-off program available in the conventional illumination control terminal is set to turn off the lamps only once at a set time. In order to periodically turn off the lamps as a countermeasure against the event that the lamps are turned on again by a third person, there is a need to prepare an increased number of turning-off programs and to thoroughly execute the turning-off programs thus prepared. This requires a user managing the illumination control system to invest a considerable amount of time in preparing the turning-off programs and to perform troublesome operations. Since the turning-off programs available in the conventional illumination control terminal are hard to keep the lamps thoroughly turned off, difficulties are encountered in reducing power consumption by not turning on unnecessary lamps.